pandas, good to have list as element or, just flatten it?

Asked Mar 20 '19 at 09:12

Active Mar 20 '19 at 09:15

Viewed 18 times

Suppose, I want to analyze item-purchase records

My analization function expects userid, item_ids

df analyze(user_id, item_ids):
   ..

Is it a good idea to prepare data in

user_id item_ids
1,  [3,4,5]

user_id, item_ids
1,  3
1,  4
1,  5

(with the 2nd one, I could do groupby and generate the data format I need)

I just find it hard to work with data format of ([1, [3,4,5]]) than ([1,3],[1,4],[1,5]) in intermediate steps..

edited Mar 20 '19 at 09:15

asked Mar 20 '19 at 09:12

eugene

Second is winner, check [this](https://stackoverflow.com/q/993984) – jezrael Mar 20 '19 at 09:13
1

And [this](https://stackoverflow.com/a/52563718) – jezrael Mar 20 '19 at 09:14
but in my opinion it depends, if small data and need lists, it is up to you. – jezrael Mar 20 '19 at 09:15

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